This crossword No. 12129 clues and answers were published on Wed 25 Mar 2009 and the puzzle can be visited by following The Guardian Quick Crossword No. 12129 link.
All Across Clues and Answers:
1-across – Reverse one’s decision : BACKTRACK
8-across – Terminology — custom : USAGE
9-across – Heavy — very serious : WEIGHTY
10-across – 3, of 27, for example? : CUBEROOT
11-across – Legendary Himalayan dweller : YETI
13-across – Admiral on a column : NELSON
14-across – Dainty : MIGNON
16-across – Single entity : UNIT
17-across – English county : SOMERSET
19-across – Underwater missile : TORPEDO
20-across – Broadcasting : ONAIR
21-across – Feeling badly treated : RESENTFUL
All Down Clues and Answers:
1-down – Dark red root eaten as a vegetable : BEETROOT
2-down – : COWBOY
3-down – Ninny : TWIT
4-down – Beginning of Lent : ASHWEDNESDAY
5-down – Number of sharps or flats on a musical stave : KEYSIGNATURE
6-down – Former ticket collector on public transport : BUSCONDUCTOR
7-down – Pub game : BARBILLIARDS
12-down – Woven steel strands, used as an abrasive : WIREWOOL
15-down – Go to sleep : NODOFF
18-down – Accustom to abstain from a former habit : WEAN
This crossword has in total 22 where 12 are across and 10 are down.